Journal of Logic and Computation Advance Access originally published online on September 12, 2008
Journal of Logic and Computation 2009 19(1):199-215; doi:10.1093/logcom/exn024
This article appears in the following Journal of Logic and Computation issue: Special Issue: Logic and Computation in the Real World: CiE 2007 [View the issue table of contents]
Original Articles |
A Jump Inversion Theorem for the Degree Spectra
Faculty of Mathematics and Computer Science, Sofia University, 5 James Bourchier Blvd., 1164 Sofia, Bulgaria.
E-mail: asoskova{at}fmi.uni-sofia.bg,soskov{at}fmi.uni-sofia.bg
Received 30 September 2007.
In the present article, we continue the study of the properties of the spectra of structures as sets of degrees initiated in [11]. Here, we consider the relationships between the spectra and the jump spectra. Our first result is that every jump spectrum is also a spectrum. The main result sounds like a Jump inversion theorem. Namely, we show that if a spectrum
is contained in the set of the jumps of the degrees in some spectrum
then there exists a spectrum
such that 

and
is equal to the set of the jumps of the degrees in
.
Keywords: Turing degrees; degree spectra; forcing; Marker's extensions; enumerations
References
- Ash CJ, Jockush C, Knight JF. Jumps of orderings. Transaction of the American Mathematical Society (1990) 319:573–599.[CrossRef]
- Coles R, Downey R, Slaman T. Every set has a least jump enumeration. Journal of the London Mathematical Society (2000) 62:641–649.
[Abstract/Free Full Text] - Downey RG, Knight JF. Orderings with
th jump degree 0(
). Proceedings of the American Mathematical Society (1992) 114:545–552.[CrossRef][Web of Science] - Goncharov S, Khoussainov B. Complexity of categorical theories with computable models. Algebra and Logic (2004) 43:365–373.[CrossRef]
- Knight JF. Degrees coded in jumps of orderings. Journal of Symbolic Logic (1986) 51:1034–1042.[CrossRef][Web of Science]
- Marker D. Non
n-axiomatizable almost strongly minimal theories. Journal of Symbolic Logic (1989) 54:921–927.[CrossRef][Web of Science] - McEvoy K. Jumps of quasi-minimal enumeration degrees. Journal of Symbolic Logic (1985) 50:839–848.[CrossRef][Web of Science]
- Moschkovakis YN. Elementary induction of abstract structures. (1974) Amsterdam: North-Holland.
- Richter LJ. Degrees of structures. Journal of Symbolic Logic (1981) 46:723–731.[CrossRef][Web of Science]
- Selman AL. Arithmetical reducibilities I. Zeitschrift für Mathematische Logik und Grundlagen der Mathematik (1971) 17:335–350.[CrossRef][Web of Science]
- Soskov IN. Degree spectra and co-spectra of structures. Annuaire de lUniversité de Sofia "St. Kliment Ohridski". Faculté de Mathématiques et Informatique. Presses Univ. "St. Kliment Ohridski", Sofia (2004) 96:45–68.
| ||||||||||||||||||||||||||||||||||||||||||||||||||